A quick way to identify if a player has a bazaar is the briefcase icon shown under their name in the Forums and on their profile. If the bazaar is empty then the briefcase icon will not appear alongside the player's name.
You can also find out who has the cheapest items via the Item Market. Once you have selected an item, scroll down to see the bazaars which are currently listing the cheapest prices on offer. The most popular bazaars are shown on the front page of the Newspaper (the amount of customers and the amount of items sold determine which bazaars are featured here).
For how to edit Your Bazaar see How to edit your Profile Signature